Population genetics structure and morphometric analyses of Round Goby Neogobius melanostomus collections from Lake Erie, Presque Isle Bay, and three Erie County, Pennsylvania, streams

Open Access
Author:
Abramson, Sidney Caleb
Graduate Program:
Wildlife and Fisheries Science
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 29, 2015
Committee Members:
  • Stauffer, Thesis Advisor
  • Timothy Lee King, Thesis Advisor
  • Jeanette Lane Schnars, Thesis Advisor
Keywords:
  • round goby
  • neogobius melanostomus
  • Erie
  • Pennsylvania
  • morphometrics and meristic characters
Abstract:
The Laurentian Great Lakes represent one of the world’s most invaded freshwater systems primarily due to decades of transatlantic ships purging ballast tanks containing exotic flora and fauna. The Round Goby, Neogobius melanostomus, a benthic, Eurasian fish native to the Ponto-Caspian region of the Black and Caspian seas, was first reported in North America in the St. Claire River of Michigan in 1990 and made its way to the eastern basin of Lake Erie by the mid-1990s. The present-day distribution of Round Goby includes all five Great Lakes and many of their tributaries. The tributary invasion success of Round Goby raises the question whether these fish are exhibiting site fidelity for these systems solely for spawning purposes or spending their entire life cycle within the same stream. If the latter is true, Round Goby may be exhibiting evolutionary adaptability to localized environments and functioning as discrete populations. Studying patterns of genetic variability of Round Goby may aid in predicting future invasion success. Identifying post-invasion dispersal of Round Goby can prove to be an important management tool for predicting range expansion capabilities; moreover knowing their population genetic structure, thus promoting a better understanding of evolutionary change and mechanisms of species adaptation. The purpose of this study was to determine if lake and tributary collections of Round Gobies are distinct by comparing tissue and whole specimen samples genetically and morphologically, respectively. Using tissue samples collected from 335 individual Round Gobies obtained from 12 interspersed sample locations (tributaries [n=3], Presque Isle Bay [n=3], offshore trawls [n=4], and tributary embayments [n=3]), an initial suite of 21 novel microsatellites were developed to enable detailed population genetic analyses. Moreover, these microsatellite markers complement the limited suite of existing microsatellites and will aid in determining source locations (founder effect) for future collections of Round Goby from new invasions and/or introduction. Here I report on variation at 12 microsatellite DNA markers for 314 Round Gobies (originally 335 specimens; 21 were later removed due to extraction error and various constraints). Levels of genetic diversity were low in all collections (with 2 to 10 alleles per locus), and heterozygosity ranged from He=0.628 to He=0.703. Overall tributary collections were no more diverse than Lake Erie and Presque Isle Bay populations, genetically. Tests of population differentiation among all collections (overall FST=0.036) suggest a low level of genetic differentiation and an overall panmictic population. This result was supported by Bayesian clustering analyses in STRUCTURE, which suggested K = 1 cluster or populations. In addition, morphometric and meristic analysis were conducted on a subsample of Round Gobies (n=90) collected for genetic assays. Principle component analysis (PCA) and analysis of variance (ANOVA) were performed in order to determine whether unique morphotypes exist according to habitat occupancy. While ANOVA results suggest statistically significant phenotypic differentiation (p<0.05), these data are functions of phenotypic plasticity seen through habitat occupancy and available food source. These results implicitly support genetic analysis results as to the presence of one large panmictic, interbreeding population of Round Goby in and around the Presque Isle, Pennsylvania portion of Lake Erie and tributaries.